The rider rolls are provided on two drum winders to facilitate the winding of the roll and the building of an acceptable roll structure that can be further handled for shipping, printing etc.
A variety of different mounting structures have been provided for mounting rider rolls or rider roll beams on the winder. Such means permit limited relative movement between the opposite axial extremities of the beam. Normally the drive to one end of the rider roll beam assembly is coordinated with the drive to the opposite end so that the opposite ends of the rider roll move up and down with only limited relative movement therebetween, i.e. the plane of the rider roll is maintained substantially horizontal although there is provision to accommodate some slight movement. Attention is directed to Canadian Pat. No. 932,315, issued Aug. 21, 1972 G. W. Dorfel.
Limited relative movement of one end of the beam to the other is accommodated in mounting by mounting one end of the beam for pivotal movement about a substantially horizontal axis on an element, the movement of which is guided substantially vertical by means of the frame member at one axial end of the equipment and on which the element is moveably mounted.
It has also been proposed to utilize hydraulic cylinders to move each end of the rider roll or rider roll beam assembly as shown for example in Canadian Pat. No. 571,669, issued Mar.3, 1959, to C. D. Nitchie, which utilizes separate hydraulic cylinders positioned one at each side of the machine to adjust the length of the chain mounting for the rider roll beam. In this arrangement the position of each end of the rider roll is accurately adjusted by means of a toothed rack on each of the vertical frames.
It has also been proposed to directly couple the ends of the rider roll beam to hydraulic cylinders and to utilize these hydraulic cylinders to directly move, i.e. without the use of intermediate chains, each end of the rider roll assembly. However, the movement of the ends of the rider roll assembly relative to each other is controlled and only very limited pivotal movement is permitted.
It will be apparent that in any drive system various friction forces are encountered and the drives to each end of the rider roll beam are influenced by forces other than the forces necessary to move the beam under ideal conditions, i.e. extraneous drag forces, poor lubrication etc., so that depending on the condition of the equipment the actual pressures applied to each end of the roll assembly may vary significantly. When opposite ends of the roll assembly are permitted only limited relative movement this imbalance of the pressures is difficult to detect and may in some cases result in poorer operation of the equipment since the pressure applied to each end of the roll being wound will not be substantially the same.
The thickness or calibration of paper is not uniform and thus as a roll of paper is wound from a continuous running length the local differences in caliber tend to accummulate so that the wound roll is not normally cylindrical but may be conical or barrel shaped or the like. Pivoted movement of a rider roll beam is intended at least in part to accommodate these different shapes, particularly a conical shaped roll to permit the application of a more uniform pressure across the roll as it is being wound. Most winder structures have the ability to accommodate a minor amount of taper in the roll structure and attempt to maintain relatively uniform pressure along the length of the roll by the slight pivotal movement of the beam, however, as above indicated implanted forces may well detract significantly from this ability.
Various techniques have been devised to try and balance these pressures including sensing of the pressure between the rider roll assembly and the roll being wound at each end of the assembly, and then adjusting the pressure applied to the ends of the roll assembly accordingly (within the limits of the equipment).